Dehydrogenation with a catalytic composite containing platinum, rhenium, germanium and an alkali or alkaline earth metal

ABSTRACT

Dehydrogenatable hydrocarbons are dehydrogenated by contacting them at dehydrogenation conditions with a catalytic composite comprising a combination of catalytically effective amounts of a platinum group component, a rhenium component, a germanium component and an alkali or alkaline earth metal with a porous carrier material. A specific example of the catalytic composite disclosed herein is a combination of a platinum component, a rhenium component, a germanium component and an alkali or alkaline earth component with an alumina carrier material, wherein the components are present in amounts sufficient to result in the composite containing, on an elemental basis, 0.01 to 2 wt. % platinum, 0.01 to 2 wt. % rhenium, 0.01 to 5 wt. % germanium and 0.1 to 5 wt. % of alkali or alkaline earth metal.

United States Patent 91 Hayes [4 1 Mar. 27, 1973 DEHYDROGENATION WITH ACATALYTIC COMPOSITE CONTAINING PLATINUM, RHENIUM, GERMANIUM AND ANALKALI OR ALKALINE EARTH METAL [75] Inventor: John C. Hayes, Palatine,Ill.

[73] Assignee: Universal Oil Products Company,

- Des Plaines, Ill.

[22] Filed: Jan. 13, 1972 21 Appl. No.: 217,663

Related U.S. Application Data [60] Division of Ser. No. 13,777, Feb. 24,1970, Pat. No. 3,649,564, which is a continuation-in-part of Ser. No.839,086, July 3, 1969, abandoned.

[52] US. Cl. ..260/668 D, 260/669 R, 260/6833 [51] Int. Cl ..C07c 5/18[58] Field of Search ......260/668 D, 683.3, 669 R [56] 7 ReferencesCited UNITED STATES PATENTS 3,584,060 6/l971 Rausch ..260/683.3

5/ 1972 Stratenus ..260/683.3 8/1972 Bloch 4260/6833 PrimaryExaminer-Curtis R. Davis Attorney-JamesR. Hoatson, Jr. et al.

[ ABSTRACT the components are present in amounts sufficient to result inthe composite containing, on an elemental basis, 0.01 to 2 .wt.platinum, 0.01 to 2 wt. rheni um, 0.0l to 5 wt. germanium and 0.1 to 5wt. of alkali or alkaline earth metal.

20 Claims, No Drawings DEIIYDROGENATION WITH A CATALYTIC COMPOSITECONTAINING PLATINUM, RIIENIUM, GERMANIUM AND AN ALKALI OR ALKALINE EARTHMETAL CROSS REFERENCES TO RELATED APPLICATIONS This application is adivision of my prior, copending tion of the normal mono-olefin.Likewise, the olefin application Ser. No. 13,777 which was filed Feb.24,

i970, and is now US. Pat. No. 3,649,564, which, in turn, is acontinuation-in-part of my prior application entitled HydrocarbonConversion Process and Catalyst Therefore filed July 3, i969 andassigned Ser. No. 839,086, and now abandoned.

The subject of the present invention is broadly an improved method fordehydrogenating a dehydrogenatable hydrocarbon to produce a productcontaining the same number of carbon atoms but fewer hydrogen atoms. Inanother aspect, the present invention includes a method ofdehydrogenating normal paraffin hydrocarbons containing four to 30carbon atoms per molecule to the corresponding normal mono-olefins withminimum production of side products. Yet another aspect of the presentinvention involves the use in a dehydrogenation process of a novelcatalytic composite comprising a combination of catalytically effectiveamounts of a platinum group component, a rhenium component, a germaniumcomponent, and an alkali or alkaline earth component with a porouscarrier material. This novel composite has highly preferredcharacteristics of activity, selectivity, and stability when it isemployed in the dehydrogenation, of dehydrogenatable hydrocarbons suchas aliphatic hydrocarbons, naphthenic hydrocarbons and alkylaromatichydrocarbons.

The dehydrogenation of dehydrogenatable hydrocarbons is an importantcommercial process because of the great and expanding demand fordehydrogenated hydrocarbons for use in the manufacture of variouschemical products such as detergents, plastics, synthetic rubbers,pharmaceutical products, high octane gasoline, perfumes, drying oils,ion-exchange resins, and various other products well known to thoseskilled in the art. One example of this demand is in the manufacture ofhigh octane gasoline by using C and C mono-olefins to alkylateisobutane. Another example of this demand is in thearea ofdehydrogenation of normal paraffin hydrocarbons to produce normalmonoolefins having four to 30 carbon atoms per molecule. These normalmono-olefins can, in turn, be utilized in the synthesis of vast numbersof other chemical products. For example, derivatives of normal ,mono

.olefins have become of substantial importance to the detergent industrywhere they are utilized to alkylate an alkylatable aromatic such asbenzene, with subsequent transformation of the product arylalkane into awide variety of biodegradable detergents such as the alkylaryl sulfonatetype of detergent which is most widely used today for household,industrial, and commercial purposes. Still another large class ofdetergents produced fromthese normal mono-oleflns are the oxyalkylatedphenol derivatives in which the alkyl phenol base is prepared by thealkylation of phenol with these normal mono-olefins. Still another typeof detergent produced fromthese normal mono-olefins is a biodegradablealkylsulfate formed by the direct sulfacan be subjected to directsulfonation with sodium bisulfite to make biodegradable alkylsulfonates.As a further example, these mono-olefins can be hydrated to producealcohols which then, in turn, can be used .to produce plasticizersand/or synthetic lube oils.

Regarding the use of products made by the dehydrogenation ofalkylaromatic hydrocarbons, these find wide application in industriesincluding the petroleum, petrochemical, pharmaceutical, detergent,plastic industries, and the like. For example, ethylbenzene isdehydrogenated to produce styrene which is utilized in the manufactureof polystyrene plastics, styrene-butadiene rubber, and the likeproducts. lsoprop'ylbenzene is dehydrogenated to form alphamethylstyrene which, in turn, is extensively used in polymer formation and inthe manufacture of drying oils, ion-exchange resins, and the likematerial.

Responsive to this demand for these dehydrogenation products, the arthas developed a number of alternative methods to produce them incommercial quantities. One method that is widely utilized involves theselective dehydrogenation of dehydrogenatable hydrocarbons by contactingthe hydrocarbons with a suitable catalyst at dehydrogenation conditions.As is the case with most catalytic procedures, the principal measure ofeffectiveness for this dehydrogenation method involves the ability toperform its intended function with minimum interference of sidereactions for extended periods of time. The analytical terms used in theart to broadly measure how well a particular catalyst performs itsintended functions in a particular hydrocarbon conversion reaction areactivity, selectivity, and stability, and for purposes of discussionhere these terms are generally defined for a give reactant as follows:(1) activity is a measure of the catalysts ability to convert thehydrocarbon reactant into products at a specified severity level whereseverity level means the conditions used that is, the temperature,pressure, contact time, and presence of diluents such as H (2)selectivity usually refers to the amount of desired product or productsobtained relative to the amount of the reactant charged or converted;(3) stability refers to the rate of .change with timeof the activity andselectivity parameters obviously the smaller rate implying the morestable catalyst. More specifically, in a dehydrogenation process,activity commonly refers to the amount of conversion that takes placefor a given dehydrogenatable hydrocarbon at a specified severity leveland is typically measured on the basis of disappearance of thedehydrogenatable hydrocarbon; selectivity is typically measured by theamount, calculated on a mole percent 'of converted dehydrogenatablehydrocarbon basis, of the desired dehydrogenated hydrocarbon obtained atthe particular severity level; and stability is typicallyv equated tothe rate of change with time of activity as measured by disappearance ofthe dehydrogenatable hydrocarbon and of selectivity as measured by theamount of desired hydrocarbon produced. Accordingly, the major problemfacing workers in the hydrocarbon dehydrogenation art is the developmentof a more active and selective catalytic composite that has goodstability characteristics.

l have now found a catalytic composite which possesses improvedactivity, selectivity, and stability when it is employed in a processfor the dehydrogenation of dehydrogenatable hydrocarbons. In particular,I have determined that a combination of catalytically effective amountsof a platinum group component, a rhenium component, a germaniumcomponent, and an alkali or alkaline earth component with a porous,refractory carrier material enables the performance of a dehydrogenationprocess to be substantially improved. Moreover, particularly goodresults are obtained when this composite is utilized in thedehydrogenation of long chain normal paraffins to produce thecorresponding normal mono-olefins with minimization of side reactionssuch as skeletal isomerization, aromatization and cracking.

It is-accordingly one object of the present invention to provide a novelmethod for dehydrogenation of dehydrogenatable hydrocarbons utilizing acatalytic composite containing a platinum group component, a rheniumcomponent, a germa'niumxcomponent, or an alkali or alkaline earthcomponent combined with a porous carrier material. A second object is toprovide a novel catalytic composite having superior performancecharacteristics when utilized in a dehydrogenation process. Anotherobject is to provide an improved method for the dehydrogenation ofnormal paraffin hydrocarbons to produce normal mono-olefins. Yet anotherobject is to improve the performance of a platinum-containingdehydrogenation catalyst by using a combination of a relativelyinexpensive component,

germanium, and-a relatively expensive component,

rhenium, to beneficially interact with the platinum metal.

In brief summary, one embodiment of the present invention involves amethod. for dehydrogenating a dehydrogenatable hydrocarbon whichcomprises contacting the hydrocarbon at dehydrogenation conditions with.a catalytic composite comprising a combination of a platinum groupcomponent, a rhenium component, a

germanium component, and an alkali or alkaline earth component withaporous carrier material. The catalytic composite contains thesecomponents in amounts, calculated on an elemental basis, of about 0.01to about 2 wt. of the platinum group metal, about 0.01 to about 2 wt.rhenium, about 0.01 to about 5 wt. germanium, and about 0.1 to about 5wt. of the alkali or alkaline earth metal.

A second embodiment relates to the dehydrogenation method describedabove wherein the dehydrogenatable hydrocarbon is an aliphatic compoundcontaining 2 to 30 carbon atoms per molecule.

A third embodiment relates to the use in dehydrogenation of a novelcatalytic composite containing a combination of a platinum component, arhenium component, a germanium component and an alkali or alkaline earthcomponent with an alumina carrier material. These components are presentin this composite in amounts sufficient to result in the compositecontaining, on an elemental basis, about 0.01 to about 2 wt. of platinummetal, about 0.01 to about 2 wt. rhenium, 0.01 to about 5 wt. germanium,and about 0.1 to about 5 wt. of the alkali or alkaline earth metal. I

Other objects and embodiments of the present invention concern specificdetails regarding essential and preferred catalyticingredients,.preferred amounts of components in the composite, suitablemethods of composite preparation, suitable dehydrogenatablehydrocarbons, operating conditions for use in the dehydrogenationprocess, and the like particulars. These are hereinafter given in thefollowing detailed discussion of each of these facets of the presentinvention.

Regarding the dehydrogenatable hydrocarbon that is subjected to theinstant method, it can, in general, be an organic compound having two to30 carbon atoms per molecule and containing at least one pair ofadjacent carbon atoms having hydrogen attached thereto. That is, it isintended to include within the scope of the present invention thedehydrogenation of any organic compound capable of being dehydrogenatedto produce products containing the same number of carbon atoms but fewerhydrogen atoms, and capable of being vaporized at the dehydrogenationconditions used herein. More particularly, suitable dehydrogenatablehydrocarbons are: aliphatic compounds 'containing two to 30 carbon atomsper molecule, alkyl-aromatic hydrocarbons where the alkyl group containstwo to six carbon atoms, and naphthenes or alkyl-substituted naphthenes.Specific examples of suitable dehydrogenatable hydrocarbons are: (1)alkanes such as ethane, propane, n-butane, isobutanes, n-pentane,isopentane, neopentane, n-hexane, 2-methylpentane, 2,2-dimethylbutane,n-heptane,2-methylhexane, 2,2,3-trimethylbutane, and the like compounds;(2) naphthenes such as cyclopentane, methylcyclopentane,ethylcyclopentane, n-propylcyclopentane, cyclohexane,isopropylcyclopentane, 1,3-dimethylcyclohexane, and the likecompounds;and, (3) alkylaromatics such as ethylbenzene, n-propylb enzene,n-butylbenzene, 1,3,5-triethylbenzene, isopropylbenzene,isobutylbenzene, ethylnaphthalene, and the like compounds.

In a preferred embodiment, the dehydrogenatable hydrocarbon is a normalparaffin hydrocarbon having about four to about 30 carbon atoms permolecule. For example, normal paraffin hydrocarbons containing about 10to 15 carbon atoms per molecule are dehydrogenated by the subject methodto produce the corresponding normal mono-olefin which can, in turn,be-alkylated with benzene and sulfonated to make alkylbenzene sulfonatedetergents having superior biodegradability. Likewise, n-alkanes having12 to 18 carbon atoms per molecule can be dehydrogenated to thecorresponding normal mono-olefin which, in turn, can be sulfated orsulfonated to make excellent detergents. Similarly, n-alkanes having sixto 10 carbon atoms per molecule can be dehydrogenated to form thecorresponding mono-olefins which, can, in turn, be hydrated to producevaluable alcohols. Preferred feed streams for the manufacture ofdetergent intermediates contain a mixture of four or five adjacentnormal paraffin homologues such as C to C C to C C to C and the likemixtures.

An essential feature of the present invention involves the use of acatalytic composite comprising a combination of catalytically effectiveamounts of a platinum group component, a rheniumcomponent, a germaniumcomponent, and an 'alkali or alkaline earth component with a porouscarrier material.

Considering first the, porous carrier material, it is preferred that thematerial be a porous, adsorptive, high surface area support having asurface area of about 25 to about 500 m lg. The porous carrier materialshould be relatively refractory to the conditions utilized in thedehydrogenation process, and it is intended to include within the scopeof the present invention carrier materials which have traditionally beenutilized in hydrocarbon conversion catalysts'such as: (1) activatedcarbon, coke, or charcoal; (2) silica or silica gel, silicon carbide,clays, and silicates including those synthetically prepared andnaturally occurring, which may or may not be acid treated for example,attapulgus clay, china clay, diatomaceous earth, fullers earth, kaoline,kieselguhr, etc.; (3) ceramics, porcelain, crushed firebrick, bauxite;(4) refractory inorganic oxides such as alumina, titanium dioxide,zirconium dioxide, chromium oxide, zinc oxide, magnesia, thoria, boria,silica-alumina, silica-magnesia, chromia-alumina, alumina-boria,silica-zirconia, etc.; (5) crystalline aluminosilicates such asnaturally occurring or synthetically prepared mordenite and/or faujasiteeither in the hydrogen form or in 'a form which has been treated withmultivalent cations; and, (6) combinations of one or more elements fromthese groups. The preferred porous carrier materials are refractoryinorganic oxides, with best results obtained with an alumina carriermaterial. Suitable alumina materials are the crystalline aluminas knownas the gamma-, eta-, and theta-alumina, with gammaor eta-alumina givingbest results. In addition, in some embodiments the-alumina carriermaterial may contain minor proportions of other well known refractoryinorganic oxides suchas silica, zirconia, magnesia, etc.; however, thepreferred support is substantially pure gammaor eta-alumina. Preferredcarrier materials have an apparent bulk density of about 0.3 -to about0.7 g/cc and surface area characteristics such that the average porediameter is about to 3,000 Angstroms, the pore volume isv about 0.l toabout 1 ml/g and the surface area is about 100 to about 500 m lg. In.general, best results are typically obtained with a gamma-aluminacarrier material which. is used in the form of sphericalparticleshaving: a relatively small diameter (i.e., typically about onesixteenth inch), an apparent bulk densityof about 0.5 g/cc, a

form hydrogel spheres. The spheres are then continuously withdrawn fromthe oil bath and typically subjected to specific aging treatments in oiland an'ammoniacal solution to further improve their physicalcharacteristics. The resulting aged and gelled particles are then washedand dried at a relatively low temperature of about 300 F. to about 400F. and subjected to a calcination procedure at a temperature of about850 F. to about 1,300 F. for a period of about 1 to about 20 hours. Itis also a good practice to subject the calcined particles to a hightemperature steam treatment in order to remove as much as possible ofundesired acidic components. This manufacturing procedure effectsconversion of the alumina hydrogel to the corresponding crystallinegamma-alumina. v See the teachings of U. S. Pat. No. 2,620,314 foradditional details.

One essential constituent of the catalyst of the present invention is agermanium component. This component may be present in the composite asan elemental metal or as a chemical compound such as the correspondingoxide, sulfide, oxychloride, halide, etc., and it may be utilized in anyamount which is catalytically effective. Best'results are, in general,obtained when this component is present in an oxidation state above thatof the elemental metal; for example, as germanium dioxide. Inaddition,-it is preferred to have the germanium component uniformlydistributed throughout the carrier material. Preferably this componentis used in an amount sufficient to result in the final catalyticcomposite containing, on an elemental basis, 0.01 to about 5 wt.germanium, with best pore volume of about 0.4 ml/g, and a surface areaof about 175 mlg.

The preferred alumina carrier material may be prepared in any suitablemanner and may be synthetically prepared or naturally occurring.Whatever type of alumina is employed it may be activated prior to use byone or more treatments including drying, calcination, steaming, etc.,and it may be in a form known as activated alumina, activated alumina ofcommerce,

porous alumina, alumina gel, etc. For example, the aluresults typicallyobtained with about 0.05 to about 2 wt. germanium. This component may beincorporated in the catalytic composite in any suitable manner such asby coprecipitation or cogellation with the porous carrier material,ion-exchange with the carrier material or impregnation of the carriermaterial at any step in the preparation. It is understood that it isintended to inelude within the scope of the present invention allconventional methods for incorporating a metallic component in acatalytic composite, and the particular 'method of incorporation used isnot deemed to be an essential feature of the present invention. Oneacceptable method of incorporating the germanium component into thecatalytic composite involves coprecipitating or cogelling the germaniumcomponent during the preparation of the preferred carrier material,alumina. This method typically involves the addition of a suitablesoluble, decomposable germanium compound, such as germaniumtetrachloride, to the aluminum hydrosol. Then the resulting mixture ofthe germanium compound and hydrosol is combined with a suitable gellingagent and dropped into an oil bath, etc., as explained in detailhereinbefore. After drying and calcining the resulting gelled carriermaterial there is obtained an intimate combination of alumina andgermanium-oxide. A preferred method of incorporating the germaniumcomponent involves utilization of a soluble, decomposable compound ofgermanium to impregnate the porous carrier material. The solvent used inthis impregnation step is generally selected on the basis of thecapability to dissolve the selected germanium compound; typically, it isan aqueous, acidic solution. Thus, the germanium component may be addedto the carrier material by commingling the latter with an aqueous,acidic solution of a suitable germanium salt or compound of germaniumsuch as germanium tetrachloride, germanium difluoride, germaniumdioxide, germanium tetrafluoride, germanium di-iodide, germaniummonosulfide and the like compounds. A particularly preferredimpregnation solution comprises germanium metal dissolved in chlorinewater. In-

general, thegermanium component can be impregnated either prior to,simultaneously with, or after the platinum group and rhenium components.are added to the carrier material. However, I havefound excellentresults when the germanium componentis impregnated simultaneously withthe platinum group and rhenium components. In fact, one-preferredimpregnationsolution contains chloroplatinic acid, perrhenic acid,nitric acid, and germanium metal dissolved in chlorine water.

A second essential constituent for the catalytic composite used in thepresent invention is a platinum group component. Although the process ofthe present invention is specifically directed to the use of a catalyticcomposite containing platinum, it is intended to include other platinumgroup metals such as palladium, rhodium, ruthenium, osmium, and iridium.The platinum; group component, such as platinum, may exist within thefinal catalytic composite as a compound such as the oxide, sulfide,halide, etc., or as an elemental metal. Generally, the amount of theplatinum compared to the quantities of the other components combinedtherewith. In fact, the platinum group metallic component generallycomprises about 0.01 to about 2 percent by weight of the final catalyticcomposite,

calculated on an elemental basis. Excellent results are The platinumgroup component may be incorporated in the catalytic composite in anysuitable manner such as coprecipitation or cogellation with the carriermaterial, ion-exchange with the carrier material and/or hydrogel, orimpregnation either after or before calcination of the carrier material,etc. The preferred method of preparing the catalyst-involves theutilization of a soluble, decomposable compound of the platinum groupmetal to impregnate the porouscarrier material. For example, theplatinum group metal may be added to the carrier by commingling thelatter with an aqueous solution of chloroplatinic acid. Otherwater-soluble compounds of the platinum group metals may be employed inimpregnation solutions and include ammonium chloroplatinate,bromoplatinic acid,

- group component present in the final catalyst is small platinumchloride, dinitrodiaminoplatinum, palladium chloride, palladium nitrate,palladium sulfate, diamine palladium hydroxide, tetraminepalladiumchloride, etc. The utilization of a platinum chloride compound such aschloroplatinic acid is ordinarily preferred. In addition, it isgenerally preferred to impregnate the carrier material after it has beencalcined in order. to minimize the risk of washing away the valuableplatinum metal compounds; however, in some cases it may be advantageousto impregnate the carrier when it is in a gelled state.

Another essential ingredient of the catalyst of the present invention isthe rhenium component. This component may be present as an elementalmetal, as a chemical compound such as the oxide, sulfide, halide, etc.,or as a physical or chemical combination with the porous carriermaterial and/or other components of the catalytic composite. The rheniumcomponent is preferably utilized in an amount sufficient to result in afinal catalytic composite containing about 0.01 to about 2 wt. rhenium,calculated on an elemental basis, with best results obtained at a leyelof about 0.05 to about 1 wt. The rhenium component may be incorporatedin the catalytic composite in any suitable manner and at any stage inthe preparation of the catalyst. It is generally advisable toincorporatethe rhenium component in an impregnation step after the porous carriermaterial has been formed in order that the expensive metal will not belost due to washing and purification treatments which may be appliedtothe carrier material during the course of its production. Although anysuitable method for incorporating a catalytic component in a porouscarrier material can be utilized to incorporate the rhenium component,the preferred procedure involves impregnation of the porous carriermaterial. The impregnation solution can, in general be a solution of asuitable soluble, decomposable rhenium salt such asammonium perrhenate,sodium perrhenate, potassium perrhenate, and the like salts. Inaddition, solutions of rhenium halides such as rhenium chloride may beused; the preferred impregnation solution is, however, an aqueoussolution of perrhenic acid. The porous carrier material can beimpregnated with the rhenium component either prior to, simultaneouslywith, or after the other components mentioned herein are combinedtherewith. Best results .are ordinarily achieved when the rheniumcomponent calcium strontium, barium, and magnesium. This com ponent mayexist within the catalytic composite as a relatively stable compoundsuch as the oxide or sulfide, or in combination with one or more of theother components of the composite, or in combination with the carriermaterial'such as, for example, in the form of a metal aluminate. Since,as is explained hereinafter, the

composite containing the alkali or alkaline earth is always calcined inan air atmosphere before use in the conversion of hydro-carbons, themostv likely state this component exists in during use indehydrogenation is the metallic oxide. Regardless of what precise formin which it exists in the composite, the amount of this componentutilized is preferably selected to provide a composite containing about0.1 to about wt. of the alkali or alkaline earth metal, and, morepreferably, about 0.25 to about 3.5 wt. Best results are obtained whenthis component is a compound of lithium or potassium.

This alkali or alkaline earth component may be com bined with the porouscarrier material in any manner known to those skilled in the art such asby impregnation, coprecipitation, physical mixture, ion-exchange and thelike procedures. However, the preferred procedure involves impregnationof the carrier material either before, during or after it is calcined,or before, during or after the other materials are added to the carriermaterial. Best results are ordinarily obtained when this component isadded to the carrier material after the other metallic componentsbecause the alkali metal or alkaline earth metal acts to neutralize someof the acid used in the preferred impregnation procedure for thesemetallic components. In fact, it is preferred to add the platinum group,rhenium and germanium components to the carrier material, oxidize theresulting composite in an air stream at a high temperature (i.e.,typically about 600 to 1,000 F.), then treat the resulting oxidizedcomposite with a mixture of air and steam in order to remove residualacidity and thereafter add the alkali metal or alkaline earth component.Typically, the impregnation of the carrier material with this componentis performed by contacting the carrier material with a solution of asuitable decomposable compound or salt of the desired alkali'or alkalineearth metal. Hence, suitable compounds include the alkali metal oralkaline earth metal halides, sulfates, nitrates, acetates, carbonates,phosphates and the like compounds. For example, excellent results areobtained by impregnating the carrier material after the platinum group,rhenium and germanium components have been combined therewith, with anaqueous solution of lithium nitrate or potassium nitrate. Following theaddition of this component, the, resulting composite is dried andcalcined in an air stream as is subsequently discussed.

Regarding the preferred amounts of the various metallic components ofthesubject catalyst, I have found it to be a good practice to specify theamounts of the germanium, the rhenium and the alkali or alkaline earthcomponents as a function of the amount of the platinum group component.On this basis, the amount of the germanium component is ordinarilyselected so that the atomic ratio of the germanium metal to the platinumgroup metal contained in the composite is about 0.25:1 to about 6:1.Likewise, the amount of the rhenium component is selected to result inan atomic ratio or rhenium to platinum group metal of about 0. l :1 toabout 3:1. Similarly, the amount of the alkali or alkaline earthcomponent is ordinarily selected to produce a composite containing anatomic ratio of alkali or alkaline earth metal to the platinum groupmetal of about 5:1 to about 50:1 or more, with the preferred range beingabout :1 to about :1.

Another significant parameter for the subject catalyst is the totalmetals content which is defined to be the sum of the platinum groupcomponent, the rhenium component, the germanium component, and alkali oralkaline earth component, calculated on an elemental metal basis. Goodresults are ordinarily obtained witht'he subject catalyst when thisparameter is fixed at a value of from 0.13 to about 14 wt. with bestresults ordinarily achieved at a metals loading of about 0.5 to about6.5 wt.

Integrating the above discussion of each of the essential components ofthe catalytic composite used in the present invention, it is evidentthat a particularly preferred catalytic composite comprises acombination of a platinum component, a rhenium component, a germaniumcomponent and an alkali or alkaline earth component with an aluminacarrier material in amounts sufficient to result in the compositecontaining from about 0.05 to about 1 wt. platinum, about 0.05 to about1 wt. rhenium, about 0.05 to about 2 wt. germanium, and about 0.25 toabout 3.5 wt. of the alkali or alkaline earth metal. Accordingly,specific examples of especially preferred catalytic composites are asfollows: (1) a catalytic composite comprising 0.375 wt. platinum, 0.2wt. rhenium, 0.25 wt. germanium, and 0.5 wt. lithium combined with analu-. mina carrier material; (2) a catalytic composite'comprising 0.375wt. platinum, 0.1 wt. rhenium, 0.5 wt. germanium, and 2.8 wt. potassiumcombined with an alumina carrier material; and (3) a catalytic compositecomprising 0.375 wt. platinum, 0.375 wt. rhenium, 0.375 wt. germanium,and 0.5 wt. lithium combined with an alumina carrier material.

Regardless of the details of how the components of the catalyst arecombined with the porous carrier material, the resulting compositegenerally will be dried at a temperature of about 200 F. to about 600 F.for a period of from about 2 to 24 hours or more, and finally calcinedat a temperature of about 600 F. to about l,'100 F. in an air atmospherefora period of about 0.5 to 10 hours, preferably about 1 to about 5hours, in

order to substantially convert the metallic components to the oxideform. When acidic components are present in any of the reagents used toeffect incorporation of any one of the components of the subjectcomposite, it is a good practice to subject the resulting composite to ahigh temperature treatment with steam or with a mixture of steam andair, either after or before the calcination step described above, inorder to remove as much as possible of the undesired acidic component.For example, when the platinum group component is incorporated byimpregnating the carrier material with chloroplatinic acid, it ispreferred to subject'the resulting composite to a high temperaturetreatment with steam in order to remove as much as possible of theundesired chloride.

lt is preferred that the resultant calcined catalytic composite besubjected to a substantially water-free reduction prior to its use inthe conversion of hydrocarbons. This step is designed to insure auniform and finely divided dispersion of the metallic componentsthroughout the carrier material. Preferably, substantially pure and dryhydrogen (i.e., less than 20 vol.

ppm. H O) is used as the reducing agent in this step. The reducing agentis contacted with the calcined composite at a temperature of about 800?F. to about l,200 F. a gas hourly space velocity of about 100 to about5,000 hr., and for a period of time of about 0.5 to hours or more,effective to substantially reduce at least the platinum group component.This reduction treatment may be performed in situ as part ofa start-upsequence if precautions are taken to predry the plant to a substantiallywater-free state and if substantially water-free hydrogen is used.

Although his not essential, the resulting reduced catalytic compositemay, in some cases, be beneficially subjected to a presulfidingoperation designed to incorporate in the catalytic composite fromabout-0.05 to about 0.50 wt. sulfur calculated on an elemental basis.Preferably, this presulfiding treatment takes place in the presence ofhydrogen and a suitable sulfur-containing compound such as hydrogensulfide, lower molecular weight mercaptans, organic sulfides, etc.Typically, this procedure comprises treating the reduced catalyst with asulfiding gas such as a mixture containing a mole ratio of H to H S ofabout l0:l at conditions sufficient to effect the desired incorporationof sulfur, generallyincluding a temperature ranging from about 50 F. .upto about l,l00 F. or more. This presulfiding step can be performed insitu or ex situ.

According to the method of the present invention, the dehydrogenatablehydrocarbon is contacted with a catalytic composite'of the typedescribed above in a dehydrogenation zone' at dehydrogenationconditions.This contacting may be accomplished by using the catalyst in a fixed bedsystem, a moving bed system, a fluidized bed system, orin a batch typeoperation; however, in view of the danger of attrition losses of thevaluable catalyst and of well known operational advantages, it ispreferred to use a fixed bed system. In this system, the hydrocarbonfeed stream is preheated by any suitable heating means to the desiredreaction temperature and then passed into a dehydrogenation zonecontaining a fixed bed of the catalyst type previously characterized. Itis, of course, understood that the dehydrogenation zone may be one ormore separate reactors with suitable heating means therebetween toinsure that the desired conversion temperature is maintained at theentrance to each reactor. It is also to be noted that the reactants maybe contacted with the catalyst bed in either upward, downward, or radialflow fashion, with the latter being preferred. In'addition, it is to benoted that the reactants may be-in the liquid phase, a mixedliquid-vapor phase, or a vapor phase when they contact the catalyst,with best results obtained in the vapor phase.

Although hydrogen is the preferred diluent for use in the subjectdehydrogenation method, in some cases other art-recognized diluents maybe advantageously utilized such as steam, methane, carbon dioxide, andthe like diluents. Hydrogen is preferred because it serves thedual-function of not only lowering the partial pressure of thedehydrogenatable hydrocarbon, but also of suppressing the formation ofhydrogen-deficient, carbonaceous deposits on the catalytic composite.Ordinarily, hydrogen is utilized in amounts sufficient to insure ahydrogen to hydrocarbon mole ratio of about 1:1 to about :1, with bestresults obtained in the range of about 1.5:] to about 1021. The hydrogenstream charged to the dehydrogenation zone will typically be recyclehydrogen obtained from the effluent stream from this zone after asuitable separation step.

' selected from the lower portion of this range for the more easilydehydrogenated hydrocarbons such as the long chain normal paraffins andfrom the higher portion of this range for 'the more difficultydehydrogenated hydrocarbons such as propane, butane, and the likehydrocarbons. For example, for the dehydrogenation of C to C normalparaffins, best results are ordinarily obtained at a temperature ofabout 800 to about 950 F. The pressure utilized is ordinarily selectedat a value which is as low as possible consistent with the maintenanceof catalyst stability, and is usually about 0.1 to about 10 atmospheres,with best results ordinarily obtained in the range of about 0.5 to about3 atmospheres. In addition, a liquid hourly spaced velocity (calculatedon the basis of the volume amount, as a liquid, of hydrocarbon chargedto the dehydrogenation zone per hour divided by the volume of thecatalyst bed utilized) is selected fromv the range of about 1 to abouthr, with best" results for the dehydrogenation of long chain normalparaffins typically obtained at a relatively high space vvelocity ofabout 25 to 35 hr.'.

Regardless of the details concerning the operation of thedehydrogenation step, an effluent stream will be withdrawn therefrom.This effluent will contain unconverted dehydrogenatable hydrocarbons,hydrogen, and products of the dehydrogenation reaction. This stream istypically cooled and passed to a separating zone wherein a hydrogen-richvapor phase is allowed to separate from a hydrocarbon-rich liquid phase.In

- general, it is usually desired to recover the unreacteddehydrogenatable hydrocarbon from this hydrocarbon-.

rich liquid phase in order to make the dehydrogenation processeconomically attractive. This recovery step can be accomplished in anysuitable manner known to the art such as by passing the hydrocarbon-richliquid phase through a bed ofsuitable adsorbent material which has thecapability to selectively retain the dehydrogenated hydrocarbonscontained therein or by contacting same with a solvent having a highselectivity for the dehydrogenated hydrocarbon or by a suitablefractionation scheme where feasible. In the case where thedehydrogenated hydrocarbon is a mono-olefin, suitable adsorbents havingthis capability are activated silica gel, activated carbon, activatedalumina, various types of specially prepared molecular sieves, and thelike adsorbents. In another typical case, the dehydrogenatedhydrocarbons can be separated from the unconverted dehydrogenatablehydrocarbons by utilizing the inherent capability of the dehydrogenatedhydrocarbons to enter into several well known chemical reactions such asalkylation, oligomerization, halogenation, sulfonation, hydration,oxidation, and the like reactions. Irrespective of how thedehydrogenated hydrocarbons are separated from the unreactedhydrocarbons, a stream containing the unreacted dehydrogenatablehydrocarbons will typically be recovered from this hydrocarbonseparation step and recycled to the dehydrogenation step. Likewise,

the hydrogen phase present in the hydrogen separating zone will bewithdrawn therefrom, a portion of it vented from the system in order toremove the net hydrogen make, and the remaining portion is typicallyrecycled, through suitable compressing means, to the dehydrogenationstep in order to provide diluent hydrogen therefor.

In a preferred embodiment of the present invention wherein long chainnormal paraffin hydrocarbons are dehydrogenated to the correspondingnormal monoolefins, a preferred mode of operation of this hydrocarbonseparation step involves an alkylation reaction. In this mode, thehydrocarbon rich liquid phase withdrawn from the separating zone iscombined with a The following workingexamples are introduced toillustrate further the novelty, mode of operation, utility, and benefitsassociated with the dehydrogenation method and catalytic compositeof thepresent invention. These examples are intended to be illustrative ratherthan restrictive.

' These examples are all performed in a laboratory scale dehydrogenationplant comprising a reactor, a hydrogenseparating zone, a heating means,cooling means, pumping means, compressing means, and the like equipment.In this plant, the feedstream containing the dehydrogenatablehydrocarbon is combined with a hydrogen stream'and resultant mixtureheated to the desired conversion temperature, which refers herein to thetemperature maintained at the inlet to the reactor. The heated mixtureis then passed into contact with the catalyst which is maintained as afixed bed of catalyst particles in the reactor. The pressures reportedherein are recorded at the outlet from the reactor. An effluent streamis withdrawn from the reactor, cooled, and passed into the separatingzone wherein a hydrogen gas phase separates from a hydrocarbon-richliquid phase containing dehydrogenated hydrocarbons, unconverteddehydrogenatable hydrocarbons and a minor amount of side products of thedehydrogenation reaction. A portion of the hydrogenrich gas phase isrecovered as excess recycle gas with the remaining portion beingcontinuously recycled through suitable compressive means to the heatingzone as described above. The hydrocarbon-rich liquid phase from theseparating zone is withdrawn therefrom and subjected to analysisto'determine conversion and selectivity for the desired dehydrogenatedhydrocarbon as will be indicated in the examples. Conversion numbers ofthe dehydrogenatable hydrocarbon reported herein are all calculated onthe basis of disappearanceof the dehydrogenatable hydrocarbon and areexpressed in mole percent. Similarly, selectivity numbers are reportedon the basis of moles of desired hydrocarbon produced per 100 moles ofdehydrogenatable hydrocarbon converted.

All of the catalysts utilized in these examples are prepared accordingto the following general method with suitable modifications instoichiometry to achieve the compositions reported in each example.First, an alumina carrier material comprising 1/16 inch spheres isprepared by: forming an aluminum hydroxyl chloride sol by dissolvingsubstantially pure aluminum pellets in a hydrochloric acid solution,adding hexamethylenetetramine to the sol, gelling the resulting solutionby dropping it into an oil bath to form spherical particles of analumina hydrogel, aging, and washing the resulting particles with anammoniacal solution and finally drying, calcining, and steaming the agedand washed particles to form spherical particles of gammaaluminacontaining substantially less than 0.1 wt. combined chloride. Additionaldetails as to this method of preparing this alumina carrier material aregiven in the teachings of U. S. Pat. No. 2,620,314.

Second, a measured amount of germanium dioxide powder. is placed in aporcelain boat and subjected to a reduction treatment with substantiallypure hydrogen at a temperature of about 650 C. for about 2 hours.

The resulting grayish-black solid material is dissolved in chlorinewater to form a solution. An aqueous solution containing chloroplatinicacid,perrhenic acid and nitric acid is also prepared. The two solutionsare then intimately admixed and used to impregnate the gammaaluminaparticles. The amounts of the various reagents are carefully selected toyield final catalytic composites containing the required amounts ofplatinum, rhenium and germanium. In order to insure uniform distributionof metallic components throughout the carrier material, thisimpregnation step is performed by adding the alumina particles to theimpregnation mixture with constant agitation. The impregnation mixtureis maintained in concact with the alumina particles for a period ofabout one half hour at a temperature of 70 F.

' thereafter, the temperature of the impregnation mixture is raised toabout225 F. and the excess solution is evaporated in a period of about 1hour. The resulting dried particles are then subjected to a calcinationtreatment in an air atmosphere at a temperature of about 500 to about1,000 F. for about 2 to 10 hours. Thereafter, the resulting calcinedparticles are treated with an air stream containing from about 10 toabout 30 percent steam at a temperature of about 800 to about lO00 F.foran additional period from about 1 to about 5 hours in order tofurther reduce the residual combined chloride in the composite.

Finally, the alkali or alkaline earth metal component is added to theresulting calcined particles in a second impregnating step. This secondimpregnation step involves contacting the calcined particles with anaqueous solution of a suitable decomposable salt of the desired alkalior alkaline earth component. For the composites utilized in the presentexamples, the salt is either lithium nitrate or potassium nitrate. Theamount of this salt is carefully chosen to result in a final compositehaving the desired composition. The resulting alkali impregnatedparticles are then dried, calcined and steamed in exactly the samemanner as described above following the first impregnation step.

In all the examples the catalyst is reduced during start-up bycontacting with hydrogen at an elevated temperature and thereaftersulfided with a mixture of H and H 5.

EXAMPLEI The reactor is loaded with 100 cc's of a catalyst containing,on an elemental basis, 0.375 wt. platinum, 0.2 wt. rhenium, 0.25 wt.germanium, 0.5 wt. lithium and less than 0.15 wt. chloride. The feedstream utilizedis commercial grade isobutane containing 99.7 wt.isobutane and 0.3 wt. normal butane.

- The feed stream is contacted with the catalyst at a tem- EXAMPLE n Thecatalyst contains, on an elemental basis, 0.375 wt. platinum, 0.5 wt.germanium, 0.1 wt. rhenium, 0.5 wt. lithium, and less than 0.15 wt.combined chloride. The feed streamis commercial grade normal dodecane.The dehydrogenation reactor is operated at a temperature of 870 F., apressure of psig., a liquid hourly spacevelocity of'32 hrfl and ahydrogen to hydrocarbon mole ratio of 811. After a line-out period, a 20hour test periodis performed during which the average conversion of thenormal dodecane is maintained at a high level with a selectivity fornormal dodecene of about 90' percent.

EXAMPLE [[1 The catalyst is the same as utilized in Example 11. The feedstream is normal te tradecane. The conditions util' ized are atemperature of 840 F., a pressure of 20 psig., a liquid hourly spacevelocity of 32 hr.'l, and a hydrogen to hydrocarbon mole ratio of 8:1.After a line-out period, a 20 hour test shows an average conversion ofapproximately l2.percent and aselectivity for normal tetradecene ofabove about 90 percent.

EXAMPLE IV The catalyst contains, on an elemental basis, 0.2 wt.platinum, 0.2 wt. rhenium, 0.5 wt. germanium and 0.6 wt. lithium, withcombined chloride being less than 0.2 wt. The feed stream issubstantially pure normal butane. The conditions utilized are atemperature of 950 F., a pressure of 15 psig., a liquid hourly spacevelocity of 4.0 hr.'l and a hydrogen to hydrocarbon mole ratio of 4:1.After a line-out period, a hour test is performed and excellentconversion of the normal butane to normal butene is observed.

EXAMPLE V The catalyst contains, on an elemental basis, 0.375 wt.platinum, 0.375 wt. rhenium, 0.5 wt. germanium, 2.8 wt. potassium, andless than 0.2 wt. combined chloride. The feed stream is'commerciai gradeethylbenzene. The conditions utilized are a pressure of 15 p'sig., aliquid hourly space velocity of 32 hr. '1, a temperature of 1,050 F.,and a hydrogen to hydrocarbon mole ratio of. 8:1. During a 20 hour testperiod, at least percent of equilibrium conversion of the ethylbenzeneis observed.

It is intended to cover by the following claims all changes andmodifications of the above disclosure of the present invention thatwould be self-evident to a man of ordinary skill in the hydrocarbondehydrogenation art.

I claim as my invention:

1. A method for dehydrogenating a dehydrogenatable hydrocarbon whichcomprises contacting the hydrocarbon, at dehydrogenat'ing conditions,with a catalytic composite comprising a combination of a platinum groupcomponent, a rhenium component, a germanium component and an alkali oralkaline earth component with a porous carrier material in amountssufficient to result in a composite containing, on an elemental basis,about 0.01 to about 2 wt. of the platinum group metal, about 0.01 toabout 2 wt. rhenium, about 0.01 to about 5 wt. germanium, and about 0.1to about 5 wt. of alkali or alkaline earth metal, said germaniumcomponent being present in an oxidation state above that of theelemental metal.

2. A method as defined in claim 1 wherein the platinum group componentof the composite is platinum or a compound of platinum.

3. "A method as defined in claim 1 wherein the platinum group componentof the composite is palladiurn or a compound of palladium.

4. A method as defined in claim 1 wherein the porous carrier material isa refractory inorganic oxide.

5. A method as defined in claim 4 wherein the refractory inorganic oxideis alumina.

6 A methodas defined in claim 1 wherein the alkali or alkaline earthcomponent of the composite is a compound of lithium.

7. A method as defined in claim 1 wherein the alkali or alkalineearthcomponent of the composite is a compound of potassium.

8. A method as defined in claim 1 wherein the atomic ratio of rhenium toplatinum group metal contained in the composite is about 0.1:] to about3:1, wherein the atomic ratio of germanium to platinum group metalcontained in the component is about 0.25:1 to about 6:1 and wherein theatomic ratio of alkali or alkaline earth metal to platinum group metalcontained in the composite is about 5:1 to about 50:1.

9. A method for dehydrogenating a dehydrogenatable hydrocarboncomprising contacting the hydrocarbon, at dehydrogenating conditions,with a catalytic composite comprising a combination of a platinumcomponent, a rhenium component, a germanium component and an alkali oralkaline earth component with an alumina carrier material in amountssufficient to result in a composite containing, on an elemental basis,about 0.01 to about 2 wt. of the platinum metal,

about 0.01 to about 2 wt. rhenium, about 0.0l to about 5 wt. germanium,and about 0.1 to about 5 wt. of the alkali or alkaline earth metal, saidgermanium component being present in an oxidation state above that ofthe elemental metal.

10. A method as defined in claim 9 wherein the composite contains,- onan elemental basis, about 0.05 to about 1 wt. platinum, about 0.05 toabout 1 wt. rhenium, about 0.05 to about 2 wt. germanium, and about 0.25to about 3.5 wt. of the alkali or alkaline earth metal.

11. A method as defined in claim 9 wherein the alkali or alkaline earthcomponent of the composite is a compound of lithium. I

12. A method as defined in claim 9'wherein the alkali or alkaline earthmetal component of the composite is a compound of potassium.

13. A method as defined in claim 9 wherein the atomic ratio of rheniumto platinum contained in the composite is about 0.1:1 to about 3:1,wherein the atomic rate of germanium to platinum contained in thecomposite is 0.25:1 to about 6:1, and wherein the atomic ratio of alkalior alkaline earth metal to platinum contained in the composite is about:1 to about 50:1.

14. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is admixed with hydrogen when it contacts the catalyticcomposite.

15. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is an aliphatic compound containing two to 30 carbon atomsper molecule.

16. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a normal paraffin hydrocarbon containing about four to 30carbon atoms per molecule.

17. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a normal paraffin hydrocarbon containing about 10 toabout 15 carbon atoms per molecule.

18. A method as defined in claim 1 wherein-said dehydrogenatablehydrocarbon is an alkylaromatic, the alkyl group of which contains twoto six carbon atoms.

19 A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a naphthene.

20. A method as defined in claim 1 wherein said dehydrogenationconditions include a temperature of about 700 to about 1,200 F., apressure of about 0.1 to about 10 atmospheres, a liquid hourly spacevelocity of about 1 to about 40 hr] and a hydrogen to hydrocarbon moleratio of about l:l to about 20:1.

2. A method as defined in claim 1 wherein the platinum group componentof the composite is platinum or a compound of platinum.
 3. A method asdefined in claim 1 wherein the platinum group component of the compositeis palladium or a compound of palladium.
 4. A method as defined in claim1 wherein the porous carrier material is a refractory inorganic oxide.5. A method as defined in claim 4 wherein the refractory inorganic oxideis alumina.
 6. A method as defined in claim 1 wherein the alkali oralkaline earth component of the composite is a compound of lithium.
 7. Amethod as defined in claim 1 wherein the alkali or alkaline earthcomponent of the composite is a compound of potassium.
 8. A method asdefined in claim 1 wherein the atomic ratio of rhenium to platinum groupmetal contained in the composite is about 0.1:1 to about 3:1, whereinthe atomic ratio of germanium to platinum group metal contained in thecomponent is about 0.25: 1 to about 6:1 and wherein the atomic ratio ofalkali or alkaline earth metal to platinum group metal contained in thecomposite is about 5:1 to about 50:1.
 9. A method for dehydrogenating adehydrogenatable hydrocarbon comprising contacting the hydrocarbon, atdehydrogenating conditions, with a catalytic composite comprising acombination of a platinum component, a rhenium component, a germaniumcomponent and an alkali or alkaline earth component with an aluminacarrier material in amounts sufficient to result in a compositecontaining, on an elemental basis, abOut 0.01 to about 2 wt. % of theplatinum metal, about 0.01 to about 2 wt. % rhenium, about 0.01 to about5 wt. % germanium, and about 0.1 to about 5 wt. % of the alkali oralkaline earth metal, said germanium component being present in anoxidation state above that of the elemental metal.
 10. A method asdefined in claim 9 wherein the composite contains, on an elementalbasis, about 0.05 to about 1 wt. % platinum, about 0.05 to about 1 wt. %rhenium, about 0.05 to about 2 wt. % germanium, and about 0.25 to about3.5 wt. % of the alkali or alkaline earth metal.
 11. A method as definedin claim 9 wherein the alkali or alkaline earth component of thecomposite is a compound of lithium.
 12. A method as defined in claim 9wherein the alkali or alkaline earth metal component of the composite isa compound of potassium.
 13. A method as defined in claim 9 wherein theatomic ratio of rhenium to platinum contained in the composite is about0.1:1 to about 3:1, wherein the atomic rate of germanium to platinumcontained in the composite is 0.25:1 to about 6:1, and wherein theatomic ratio of alkali or alkaline earth metal to platinum contained inthe composite is about 5:1 to about 50:1.
 14. A method as defined inclaim 1 wherein said dehydrogenatable hydrocarbon is admixed withhydrogen when it contacts the catalytic composite.
 15. A method asdefined in claim 1 wherein said dehydrogenatable hydrocarbon is analiphatic compound containing two to 30 carbon atoms per molecule.
 16. Amethod as defined in claim 1 wherein said dehydrogenatable hydrocarbonis a normal paraffin hydrocarbon containing about four to 30 carbonatoms per molecule.
 17. A method as defined in claim 1 wherein saiddehydrogenatable hydrocarbon is a normal paraffin hydrocarbon containingabout 10 to about 15 carbon atoms per molecule.
 18. A method as definedin claim 1 wherein said dehydrogenatable hydrocarbon is analkylaromatic, the alkyl group of which contains two to six carbonatoms.
 19. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a naphthene.
 20. A method as defined in claim 1 whereinsaid dehydrogenation conditions include a temperature of about 700* toabout 1,200* F., a pressure of about 0.1 to about 10 atmospheres, aliquid hourly space velocity of about 1 to about 40 hr. 1 and a hydrogento hydrocarbon mole ratio of about 1:1 to about 20:1.